This invention relates to centrifugal blowers and centrifugal blower systems, and more particularly to freezer systems utilizing such centrifugal blowers and, specifically, to an improved centrifugal blower assembly for use in such systems.
Large centrifugal or so-called "squirrel cage" blowers are used in deep-freeze storage systems of the type by which commercial quantities of food products are quickly frozen or flash-frozen and maintained at temperatures at down to -40.degree. F. Such blowers may, for such use, be carried on shafts which are horizontally mounted within large equipment housings for being turned by large electric motors of horsepower sufficient for delivering immense volumes of super-cooled air into rooms in which food products are to be maintained at such extremely low temperatures. Because of rotational accelerations upon startup and extreme thermal stresses in materials because of the extremes of temperature, such centrifugal blowers have been known to experience a failure at the point of securement of the blower hub to the shaft.
A conventional freezer system installation utilizing such centrifugal blowers may involve the placement of multiple freezer blower housings in proximal relationship. Upon the failure of any given such blower resulting from failure at the point of its hub securement to the shaft may require that only a single blower be replaced and under circumstances requiring that the refrigeration facilities continue to be maintained in operation, such as for the preservation of foodstuffs which are in the refrigerated premises.
When the blower shaft may be several inches in diameter, and where the entire assembly weigh several hundred pounds, it is difficult enough merely to remove the shaft in its entirety from the blower cabinet and cooler assembly. However, where there are adjacent blower units, which continue in operation, distributing large volumes of super-cooled air at high velocity, the complexities and logistics of removing and repairing a blower assembly are traumatic and immense. Such repair and replacement as would be dictated by failure of the point of securement of the blower hub to the shaft might, for example, typically require that workmen carry out the repairs while exposed to the deep-freeze environment of -40.degree. F., where wind-chill equivalent temperatures might be far below such temperature because of the moving volumes of air.
Thus, existing blower technology as utilized in such refrigeration systems presents not only extremes of conditions and difficulties of replacement; there are, in addition, extraordinary costs of both manpower as well as disruption of normal operations while repairs and replacements are effected, greatly adding to the expense of maintaining such large systems, as well as requiring the need for highly skilled, highly paid maintenance personnel, whose talents and efforts might desirably better be applied to other technical areas in the facilities utilizing such systems.
In general, it has been known to provide centrifugal assemblies of the type where the blower assembly hubs may be slid off the shaft after the shaft is removed from any equipment in which the blower is used, such as one of the above blower cabinets. If there are multiple blower cabinets located in proximal relationship, removing one blower may require the removal of adjacent blowers. If the blowers are of extremely large size, replacement may entail opening holes into the walls of the structures containing such blowers so that the large shafts may be removed for permitting replacement of the blower wheels themselves.